1. Field of the Invention
The present invention relates to a graph display control apparatus for displaying a graph image corresponding to a function expression, an electronic device, and a graph display method.
2. Description of the Related Art
Conventionally, in a scientific electronic calculator (graph scientific electronic calculator) having a graph display function, if an arbitrary function expression, y=f(x), is input, a graph image corresponding to this input function expression is displayed on a display unit.
Here, there is such a case that, as regards the above-mentioned graph image, it is desired to view a variation of the graph image by varying a coefficient value of a term of the function expression. In such a case, such a graph scientific electronic calculator has been thought that, in a state in which a quadratic function expression, y=AX2+X+1, for instance, is input, a dedicated screen for setting a numerical value of a coefficient A of this function expression is displayed, and an initial value (Start), a final value (End) and a variation interval (Pitch) of the coefficient A are input and set on this dedicated screen. Thereby, graph images corresponding to the respective function expressions corresponding to the variation of the numeral value of the coefficient A are displayed as dynamic graphs on the display unit (see, for example, Jpn. Pat. Appin. KOKAI Publication No. H09-282475).
In addition, recently, such a graph scientific electronic calculator has been thought that a slider, which varies the numerical value of the coefficient A in a range between a set minimum value and a set maximum value, is displayed, and the tab of the slider is moved, thereby displaying a graph image corresponding to a function expression of a coefficient value which corresponds to the movement position of this tab.
In the above-described conventional graph scientific electronic calculator, when the characteristics of a desired function expression including a coefficient and the characteristic point thereof are to be analyzed, it is necessary to set the coefficient value of this function expression at a specific numerical value, and to display the corresponding graph image.
However, in such a graph scientific electronic calculator that the coefficient value can be varied only within a predetermined variation interval between the set initial value and final value of the coefficient value, it is difficult to precisely make the coefficient value agree with the above-mentioned specific numerical value.
In addition, also in a graph scientific electronic calculator in which the above-described coefficient value is varied by moving the tab of the slider, in order to precisely make the coefficient value agree with the specific numerical value, the numerical value variation amount corresponding to a movement unit (e.g. one display dot) of the tab has to be finely set. In this case, such a problem arises that the coefficient value cannot largely be varied.
The present invention has been made in consideration of the above problems, and the object of the invention is to provide a graph display control apparatus, an electronic device and a control program thereof, wherein when the numerical value of a coefficient included in a function expression is varied in accordance with a user operation and a graph image corresponding to this function expression is displayed, the numerical value of the coefficient can be quickly and easily varied to a specific numerical value, and a graph image corresponding to a function expression including this coefficient can be displayed.